accel/ivpu: Wait for CDYN de-assertion during power down sequence

During power down, pending DVFS operations may still be in progress
when the NPU reset is asserted after CDYN=0 is set. Since the READY
bit may already be deasserted at this point, checking only the READY
bit is insufficient to ensure all transactions have completed.

Add an explicit check for CDYN de-assertion after the READY bit check
to guarantee no outstanding transactions remain before proceeding.

Fixes: 550f4dd2cedd ("accel/ivpu: Add support for Nova Lake's NPU")
Reviewed-by: Maciej Falkowski <[e-mail]>
Reviewed-by: Jeff Hugo <[e-mail]>
Signed-off-by: Karol Wachowski <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

drivers/accel/ivpu/ivpu_hw_btrs.c

···
 	return REGB_POLL_FLD(VPU_HW_BTRS_MTL_PLL_STATUS, LOCK, exp_val, PLL_TIMEOUT_US);
 }
 
+static int wait_for_cdyn_deassert(struct ivpu_device *vdev)
+{
+	if (ivpu_hw_btrs_gen(vdev) == IVPU_HW_BTRS_MTL)
+		return 0;
+
+	return REGB_POLL_FLD(VPU_HW_BTRS_LNL_CDYN, CDYN, 0, PLL_TIMEOUT_US);
+}
+
 int ivpu_hw_btrs_wp_drive(struct ivpu_device *vdev, bool enable)
 {
 	struct wp_request wp;
···
 	if (ret) {
 		ivpu_err(vdev, "Timed out waiting for NPU ready status\n");
 		return ret;
+	}
+
+	if (!enable) {
+		ret = wait_for_cdyn_deassert(vdev);
+		if (ret) {
+			ivpu_err(vdev, "Timed out waiting for CDYN deassert\n");
+			return ret;
+		}
 	}
 
 	return 0;

drivers/accel/ivpu/ivpu_hw_btrs_lnl_reg.h

···
 #define VPU_HW_BTRS_LNL_PLL_FREQ				0x00000148u
 #define VPU_HW_BTRS_LNL_PLL_FREQ_RATIO_MASK			GENMASK(15, 0)
 
+#define VPU_HW_BTRS_LNL_CDYN					0x0000014cu
+#define VPU_HW_BTRS_LNL_CDYN_CDYN_MASK				GENMASK(15, 0)
+
 #define VPU_HW_BTRS_LNL_TILE_FUSE				0x00000150u
 #define VPU_HW_BTRS_LNL_TILE_FUSE_VALID_MASK			BIT_MASK(0)
 #define VPU_HW_BTRS_LNL_TILE_FUSE_CONFIG_MASK			GENMASK(6, 1)